The collection and analysis of retail sales information is an important part of a manufacturer or distributor's marketing and advertising strategy. A manufacturer can better target its marketing resources if up to date information regarding product sales performance is known. One way of collecting this information is to survey product stocking information from various retail locations. The process can be time consuming because there may be many retail outlets in a certain area. Further, it is not always possible to obtain accurate or timely records from the owner of a store. Thirdly, some retailers infrequently order shipments for restocking. It is difficult for a manufacturer to obtain up to date clues about the performance of its products from these retailers.